The Burren and Cliffs of Moher Geopark: Evidence in the rocks

The subject of Global Climate Change is increasingly being referred to as ‘the most pressing issue of our time’ by independent researchers, government scientists, activists, political organisations and the media. Changing climate means different weather patterns which will directly affect; how and where crops grow, animal and bird migrations, changes in ocean current circulation, droughts, flooding, soil erosion and the availability of fresh drinking water.

For Ireland, We can expect the average temperature to rise in the future. The average temperature in the years 2021 to 2060 will be 1 to 1.5°C higher compared to the years 1961 to 2000. For the same years, Met Eireann, (the Irish Meteorological Service) through its Community Climate Change Consortium for Ireland (C4I) is predicting wetter winters and drier summers.

Climate change clearly alters ecology and it has recently been demonstrated in a study of soil mites that evolution can be affected by ecology far quicker than has previously been thought. “What this study shows for the first time is that evolution and ecology go hand-in-hand,” explained co-author Tim Benton, professor of population ecology at the University of Leeds, UK. When animals at the bottom of the food chain are affected there can be a rapid, though difficult to predict knock-on effect further up the food chain which will affect humans directly. The open access publication on soil mites, ‘Eco-evolutionary dynamics in response to selection on life-history’, is published in Ecology Letters (2013).

Past Climate Change

For geologists there has never been any doubt about global climate change. We can see the evidence of ancient coal deposits in Antarctica over 250 million years ago, tropical coral seas in Europe over 330 million years ago and large lakes in the Sahara 250,000 years ago, not to mention the large ice sheets which covered Ireland until 15,000 years ago. In many cases there is good evidence that major climate changes were responsible for mass extinction events.

The major issue today is the effect that Human activities are having on climate change. Climate change would happen today even if there were no humans on Earth; in order to evaluate the added effect of Humans we must first understand the underlying non-human changes.

Evidence for past climate change in the Burren.

The rocks in the Burren and Cliffs of Moher Geopark show abundant evidence for past climate change. The most obvious is the evidence for the last Ice age.

Fig. 1 Glacial striations at the Flaggy Shore

Glacial striations are the scratch marks formed from rocks trapped in thick sheets of ice being dragged over bedrock. The orientation of these scratch marks shows us the direction travelled by the ice.

Fig. 2 Glacial erratic at Doolin

Glacial erratics (Fig. 2) are boulders that have been picked up and carried by ice and then dropped and left behind after the ice has melted.

The last glaciation affected the surface of the Burren but much further back in time, deep within the bedrock of the Burren we can see evidence of climate change from over 300 million years ago.

The Burren Terraces: Evidence for Climate Change 330 million years ago.

Fig. 3 Limestone terrace near Blackhead.

The Limestone terraces of the Burren exposed along the coast road near Poulsallagh and elsewhere are formed by preferential erosion of clay layers within the limestone.

Fig. 4 Limestone terraces near Ailwee.

The limestones of the Burren contain abundant fossil corals and other marine organisms which indicate that they were formed in a shallow tropical sea. The clay layers are different and are thought to represent soil horizons that formed during periods of lower sea level when the limestone was exposed above sea level. There are nine such clay layers and this pattern of marine limestone followed by soil clay layers followed by marine limestone etc indicates that sea level was rising and falling in a cyclic pattern.

As we find similar cycles in limestone of the same age in the UK and the USA we know this was not a local event but a global one. The sea level was rising and falling in response to ice caps forming and melting during an ice age similar to the recent one that left the glacial erratics around the Burren. So, large scale polar ice caps form regularly on Earth and are a natural part of global climate change.

What causes Climate Change?

There are two main factors that control climate change; the amount of solar energy that reaches the Earth’s atmosphere and the amount of heat energy that leaves the Earth’s atmosphere. Contributing to the second of these factors is the slow drifting of the continental plates which constantly reorganize the amount and distribution of land on the Earth’s surface as well as causing the eruption of volcanoes.

Subtle changes in the orbit of Earth around the Sun and slight changes in the tilt of the Earth’s axis are thought to be the main long term contributors to the variation in the amount of solar energy that enter the atmosphere from the sun. These variations are thought to be cyclic and are known as Milankovitch cycles after Milun Milankovitch who first identified the mathematical models that predict these cycles in 1920.

These cycles affect the Earth on different time scales from 21,000 to 41,000 to 100,000 years

Factors that influence the amount of energy that leaves the atmosphere include volcanic gases and dust, biogenic and natural carbon dioxide and man-made carbon dioxide and other ‘industrial’ gases.

What can we do?

We cannot change the orbit of the Earth or the amount of energy being delivered by the Sun but we can take responsibility for the amount of carbon dioxide (CO2) and other industrial gases that we release into the atmosphere. Our carbon footprint is a measure of the amount of CO2 emissions each of us causes in our daily lives through our travel, energy use and lifestyle. By reducing the amount of fossil fuels being burned we can directly reduce our carbon footprint. As most of our energy comes from burning fossil fuels, reducing our energy usage will automatically reduce our carbon footprint. You can measure your carbon footprint at the Environmental Protection Agency. Burren Ecotourism is a network of businesses in the Burren that are dedicated to sustainable tourism and have implemented a range of energy saving and waste water management strategies to reduce the impact on the atmosphere.